With the development of technology, a network using a variety of communication protocols plays an important role in various aspects of daily work, study, and life. Performance of such a network is thus a major concern. A Maximum Transmission Unit (MTU) refers to a maximal size of a data packet that can pass through a layer of a communication protocol, and is defined as the sum of a Maximum Segment Size (MSS) and a header length in bytes. In establishing a link of a communication protocol such as a Transmission Control Protocol (TCP), a user terminal and a server will negotiate and exchange MTUs with each other through handshake messages. The smaller MTU of the MTU of the user terminal and the MTU of the server is selected as an MTU to be used in network data transmission after the link is established. In establishing the TCP link, no data packet sent by the user terminal or the server will have a size exceeding the negotiated MTU.
A path MTU is a maximal size of a data packet that can pass through a network path. Both a data packet sent by a user terminal and that by a server may be transmitted as a whole via the path when the path MTU is no less than the negotiated MTU. For example, both the MTU of the user terminal and the MTU of the server may be 1,500 bytes. Then the negotiated MTU negotiated by the user terminal and the server may also be 1,500 bytes. When the path MTU is no less than 1,500 bytes, a data packet sent by the user terminal or the server may be transmitted in its entirety via the network path. However, when the path MTU is smaller than the negotiated MTU, for example, when the path MTU is smaller than 1,500 bytes, a data packet sent by the user terminal or the server may be transmitted as segments, leading to reduced network performance.